(I’m an adoptee who hopes to adopt in the future, but currently has young birth children.) Im sure lots of what I say, you’ll have thought through already so feel free to discount it. 🙂 I don’t personally have twins, but if the twins will be your first children, I think the initial impact would be greater. I’d be thinking about the age they’re functioning at and any developmental delay. With older children, they way they ‘need’ you can be expressed differently to a younger a child and you can do different activities with each. With very young children, when they need you they can be all over you. There’s can be lots of physically clinging, pulling hair, hitting out in frustration etc. depending on age. It’s two young children needing your complete attention all the time, so those first weeks could feel like an even bigger, more intense change.
The disturbed sleep can be intense. My birth daughter is up regularly at the moment between 3-5am, which is a developmentally normal phase, but with two (and two who had a difficult time and are in a new place) that could intensify as they’re bouncing off the other, so I’d have plans for if they both wake at the same time. Equally, their presence could help the other one sleep better, but it’s worth having a plan in place for if they keep each other up. Also, of course, this would be similar for any siblings who are both pre-schoolers.
My children have a 6y age gap, so I understand why doing similar activities with young children of similar age can be a draw, but I’d say it makes it harder to carve out individual time because their routines are the same. You have to make the time because one isn’t at school while the other isn’t etc.
I think one focus with any young sibling set would be how to spend time individually with each, to help them attach. Twins can be lumped together a lot and so a real focus on identifying and encouraging each of their personal interests would be good. I’d probably also be thinking about trauma bonds and how they might be affected by these, as a pp said.
Otherwise, I think I’d be looking at how you cope in different stages. For example, the impact of the teenage years with two children of an identical age potentially displaying traumatised behaviours. When I think about my own teenage years, I think this stage would have been even harder for my parents if I had a sibling with a close relationship and if potentially some behaviours fed off each other. For school, similarly, if they need extra support, it’s two children to fight for simultaneously if they both develop issues at the same time.
The last thing would be contact, so if they have any contact with family members, what impact is that likely to have? If, for example, you put a lot into helping them develop as individuals but then at contact they’re seen only as a single unit. Obviously they may well not be, but might be something I’d look into alongside how their roles in the birth family played put up to now.
Wishing you all the best with matching if you go ahead ☺️